In one type of air compressor, an electric motor rotates an eccentric which causes a piston to reciprocate in a cylinder. A valve plate closes an end of the cylinder and includes an inlet valve which allows air to be drawn into the cylinder from an inlet port during an intake stroke of the piston and an exhaust valve which allows compressed air to flow from the cylinder during a compression stroke of the piston. As the air is compressed, heat is released. The heat produced during compression can adversely affect the efficiency and operating life of the compressor.
In one type of air compressor, sometimes referred to as an oilless compressor, a thin piston is rigidly attached to a connecting rod. As the free end of the connecting rod is rotated by the eccentric the piston reciprocates in the cylinder and also rocks or tilts. A flexible seal extends around the perimeter of the piston to form a sliding seal as the piston reciprocates and rocks. The seal is formed from a material which does not require oil lubrication. Optionally, the interior wall of the cylinder may be coated with a low friction coating. Generally, the life of the sliding seal is the controlling factor in the service life of the compressor. One of the most significant factors in determining the operating life of the sliding seal is its maximum operating temperature. As the operating temperature of the seal increases, the life of the seal decreases. At higher operating temperatures, only a small temperature increase can significantly reduce the life of the piston seal. Consequently, it is important to design the compressor to maximize cooling of the cylinder walls and of the seal.
In prior art air compressors, a compressor was designed for a specific flow and compression capacity. Generally, the components of a compressor could not be adapted or used in a compressor having a different flow and compression capacity.